bug#59141: 28.1.90; Face :extend when all the line but trailing \n is invisible

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: 59141@debbugs.gnu.org,  Eli Zaretskii <eliz@gnu.org>,  Abdul-Lateef
>  Haji-Ali <abdo.haji.ali@gmail.com>,  yantar92@posteo.net
> Date: Tue, 22 Nov 2022 09:52:40 +0200
> 
> > we could add ellipses in a more clean way: as a new value of the user
> > option 'outline-minor-mode-use-buttons'.  So when it's customized to
> > 'ellipsis', the ellipsis overlay will be created in a new pcase branch
> > in outline--insert-button.
> 
> Unfortunately, this is not possible to do because of a bug
> in overlay handling.  Here is a short test case:
> 
> (progn
>   (insert "ab")
>   (let ((o (make-overlay 1 2)))
>     (overlay-put o 'after-string "!"))
>   (let ((o (make-overlay 2 3)))
>     (overlay-put o 'invisible t)))
> 
> The problem is that "!" from 'after-string' is not displayed,
> even when it's on the text that is not invisible.

There's no bug here.  after-string is displayed when the end position of the
overlay is reached, and in this case the end position is invisible, so it is
skipped.